Nueces Basin and Bay Area Stakeholders Committee

April 21, 2010

Overview of Edwards Aquifer Authority Operations in Nueces Basin

Topics of Discussion

• EAA purpose and boundary• EAA activities in Nueces Basin• Impacts on Instream Flows in Nueces

Basin

Edwards Aquifer = San Antonio Segment of the Balcones Fault Zone Edwards Aquifer

A

B

Generalized Edwards Aquifer Cross Section

A B

EAA Operations in Nueces Basin

• Regulatory programs – quantity and quality• Data collection – quantity, quality, rainfall• Current research projects:

– Flowpath studies:• Alluvial underflow• Tracer testing in Kinney County• COE Nueces Basin Feasibility Study – HSPF• Recharge and recirculation – Phase III/IV

complete• Cloud Seeding – Uvalde, Medina, Bandera Co.

EAA Operations in Nueces Basin (contd.)

• Range management cost share• Existing recharge dams in Nueces Basin (three):

– Seco Creek– Parkers Creek– Middle Verde Creek

• Planning/oversight Groups– SCTWAC– State water planning process - Region L– Edwards Aquifer RIP – Recharge Subcommittee

Existing EAA-operated structures

• Authority operated structures:– All in Medina County

• Parkers Creek Dam – built 1974• Middle Verde Creek Dam – built 1978• San Geronimo Creek Dam – built 1979• Seco Creek Dam/Channel – built 1982

– Authority has surface water diversion permits for the four structures

– Authority also has Class V injection well permits for the Verde and Seco creek structures

San Geronimo Creek Dam

Middle Verde Creek Dam

Parkers Creek Dam

Seco Channel

South Central Texas Regional Water Planning Process – Region L

• – 1998 to present– 2001 and 2006 versions for Region L Plan

• 2001 version had more recharge scenarios than 2006 version

• 2006 version primarily contains Trans- Texas management scenario (L-18)

• Draft 2011 plan – recharge scenarios identical/very similar to 2006 plan

Definition Number 1 Types of Recharge Structures:

TYPE 2

NORTH SOUTH

Recharge Area

Hold for directinfiltration

TYPE 1Catchment Area

Hold for ReleaseEdwards

LimestoneEngineeredStructure

EngineeredStructure

Balcones Fault Zone

Glen Rose Formation

Confining Beds

Glen Rose Formation

Edwards Limestone

Commonly Analyzed Recharge Sites

SanAntonio

Hays

Comal

Bexar

MedinaUvaldeKinney

UpperBlanco

UpperVerde

UpperHondoUpper

SabinalUpperDry Frio

Montell Concan

CiboloDam No. 1

LowerVerdeLower

Hondo

Indian CreekLower

Sabinal

LowerBlanco

LowerFrio

SanGeronimo

LEGEND

Type 1 ProjectType 2 ProjectEdwards Aquifer Recharge ZoneSaline Water Line

Recharge Enhancement Studies (contd.)

• 2006 Region L Plan (contd.)– Contains recharge programs 2A, 2B, and

2C– Program 2A has the most scenarios,

includes the 2B and 2C scenarios, plus others

– Section 4C.20 of plan recommends:• Implement Program 2C by 2020• Expand to Program 2A by 2060

Recharge Enhancement Studies (contd.)

• 2006 Region L Plan (contd.)– Program 2A

• Indian Creek (with diversion to Dry Frio)• Lower Frio, Sabinal, Hondo, Verde• Lower Blanco, Cibolo #1, Dry Comal• San Geronimo (Upper San Geronimo)• Northern Bexar and northern Medina counties• Salado Creek FRS modifications

Recharge Enhancement Studies (contd.)

• 2006 Region L Plan (contd.)– Program 2A (contd.)

• Northern Bexar and Northern Medina counties (small Type 2 structures)

–Limkiln–Culebra–Deep Creek–Salado Dam No. 3–Government Canyon

Impacts on Instream Flow

• Impacts on lower Nueces Basin are minimal, pluses and minuses, qualitative estimates at this time

• Some activities enhance and some diminish flows

• Mitigation (if needed) is envisioned in all project concepts

Overview of EAA Nueces Basin Activities

END of SLIDES

John Hoyt, P.G.Edwards Aquifer Authoritywww.edwardsaquifer.org